How do birth control pills work?

I've just had my first condom break ever. I'm on the pill, so I'm not worried about pregnancy, but a couple of days afterwards I had yeast infection-like symptoms — no unusual discharge, just itching. If I pick up some over-the-counter yeast infection medication and the symptoms go away, would I be safe to assume that was the problem? Or should I definitely go in for an STI check?

I've been on birth control pills for eight years and I'm thinking about trying a few months off them. They were prescribed when I was pretty young because of very irregular periods. I also was involved in a monogamous relationship for a number of years, so they were convenient. Now I have no steady partner, and am really curious to see how I feel without taking these pills. Would it be ok to go off them at the end of my pill pack or should I consult someone at health services first? If I go off for a few months and my periods are as horrendous as they were when I was younger, would it be safe to start up again on my own (I usually just see someone once per year for pill checks)?

I care for my girlfriend, whom I have been seeing for a few months now. I have no problem maintaining an erection when she performs oral sex on me. In fact I can climax twice in a relatively short time. We have, however, been unable to actually engage in intercourse, since when we go to put on the condom, I lose my erection. I'm not really having too much of a problem getting erect (i.e., I get an erection, and may lose it early on, but I am able to get and maintain another one for oral sex). What could be the problem? Stress? A lack of physical attraction? I will be grateful for any answer you can provide me.

I noticed that you have information on tubal ligation (surgical sterilization for women), but not on Essure. Can you tell me more about it? What are the risks and benefits?

If my husband takes antivirals or post-exposure prophylaxis can we still have sex with a condom and still complete the process like normal? It is affecting our sex life because he does not want to infect me. I don't want to be infected but I knew what I was getting into from the start. I might start PrEP as it is now available to me. What are your thoughts?